Shrouded drill bit



Nov. 4, 1941. w. w. GIPSON 2,261,546 4 SHROUDED DRILL BIT 'Filed Dec. 8, 1939 3 N V E N TO R WILLARD W.GIPSON Patented Nov. 4, 1941 umw STATE- Para 2,2iii546 oaaica snaoomao DRILL arr Willard w. Gipson, Taft, cam.- Application December 8, 1939, Serial No. 308,200

2 Claims.

This invention relates to drill bits of the type having a. plurality of roller cutters for drilling hard formations in deep wells, and is particularly directed to anarrangement of a shroud or enclosure for said cutters which will provide an opening through which the cutters may extend to be operative, but which will prevent their loss if the cutter support means should fail.

Heretofore roller cutter bits have been provided with shrouds which are adapted to extend only over the upper portion of th rollers to direct downwardly the stream of drilling mud fiuid which is used to wash the cuttings out of pin or spindle onwhich they rotate should become fractured. The loss of such cutters in very deep bore holes is quite frequent and necessitates the removal of the long drill pipe and the insertion of some sort of fishing tool to remove the broken parts. If these parts are not removed they interfere seriously with a new drill bit and may damage it severely before being pushed aside desiredmanner. The shrouds 14 which form a principal part of this invention are substantially L'-shaped with a shank which conforms to the particular bitand is secured to body l0 and members i2 by any'suitable means such as a welded seam I5. I The outer faces of the shank portions of shrouds i4 may be recessed as at IE to provide adequate passage for mud fluldand ,cuttin'gs upwardly around the bit. The lower portion of each shroud I4 is generally at, right angles to the shank and usually extends inwardly toward the center of bit 10.

The lower faces I] of shrouds M are extended transversely toward the cutter axes as indicated in Figure 1 and may be notched or recessed, if desired, so as to enclose enough of the cutters 13 which, in this example are frusto-conlcal, but which can.be of any desired configuration or arrangement, so that the latter will be retained in the formation or reduced to small pieces by the action of the new bit. x

A second feature of this improvement is in the provision of a strong and substantial shroud. the bottom of which is spaceda predetermined distance above the lowest point on the teeth of the roller cutters so that when the latter are worn to a predetermined degree the bit will skid around on'the formation and indicate to the driller that the cutters are no longer in effective condition for further drilling. This prevents long continued rotation of ineffective bits.

These and other objects of the invention will be more fully apparent from the following description and from the appended drawing, which iftheir support pin or spindle should become broken. The lower face i! of shrouds It also serves an added purpose of being spaced a predetermined distance -A" above the lowest point on the teeth of rollers l3 so that when the teeth are worn. to a degree which will permit thebit to slide or skid on surface I! the driller will be able to tell by the behavior of the drilling apparatus that the bit has been wornso as to be inefficient. Distance A," therefore, will be somewhat less than the length of the longest teeth. In this way he will be able to replace such bits with a minimum of lost time from actual drilling operation.

Although a specific embodiment of this invention has been described and illustrated, it is to be understood that variations in its arrangement, and particularly in the configuration of the shrouds and their manner of attachment to the appended claims are embraced thereby.

forms a part of the specification .and illustrates a preferred form of the invention..

In the drawing, Figure 1 represents a bottom view of a drill bit employing frusto-conical rotary cutters and fitted with a shroud embodying body it) is provided'with downwardlyextending supports I! for a plurality of frusto-conlcal toothed cutter-sit which may be secured in any I claim: -1. A shroud for a drill bit haying spaced rotatable toothed cutters,- said shroud comprising a generally L-shaped memberhaving a shank portion shaped to conform to the body of said bit between adjacent cutters, and another portion at substantially right angles to said shank adapted to overlap a portion of-at least one of said cutters below its axis and still permit its working teeth to extend beyond the outer face of said shroud.

2. A shroud for a drill bit having spaced rotatable toothed cutters, said shroud comprising a generally L-shaped member having a shank portion shaped to conform to the body-of said bit and another portion at substantially right angles to said. shank and notched to extend beneath at least a portion of on of said toothed cutters below its axis of rotation.

WILLARD W. GIPSON. 

